(1) Field of the Invention
The present invention relates to a multimedia optical disc which stores multimedia data, and to an apparatus and a method for reproducing the multimedia optical disc, more specifically to an improvement in the reproduction of movie applications.
(2) Description of the Prior Art
Currently, laser discs and video CDs (Compact Discs) are known as optical media in which audio information and moving picture information are recorded to be reproduced by dedicated apparatuses.
Laser discs are optical discs with a diameter of about 30 cm storing about an hour of analog moving picture data. Laser discs have been used as media for storing movies or music video works. However, since laser discs are bulky and hard to carry or stock, other media which are more compact than the laser discs have been sought.
Video CDs have achieved the above purpose by enabling moving picture data to be recorded on CDs. The CDs have a diameter of 12 cm and at first were used to store only audio data. The video CDs adopt a digital data compression method called MPEG (Moving Picture Experts Group) which has a high compression rate. The resolution of video CDs is as low as 352xc3x97240 though they are compact in size.
The above laser discs and video CDs, on the other hand, have the following limitation on the voice and sub-pictures. That is, since audio information is recorded in a channel, it is impossible to deal with a plurality of languages. Furthermore, the sub-picture data is recorded as a part of moving picture data and it is impossible to deal with a plurality of languages. Therefore, Japanese, English, French, and Germany versions of voices and subtitles for the same moving picture data, for example, cannot be recorded in the above conventional discs.
Different versions of a movie, for example, a theater version, a no-cut version, and a TV on-air version are available. Conventionally, it was possible to record all these versions in a video CD only if the movie was short enough to record in the disc. However, this was not possible for general movie films having 1-2 hours of reproduction time.
A laser disc can store monoaural audio data (analog or digital) in four channels at maximum along with about one hour of analog moving picture data. Laser discs are mainly used for storing movie applications. However, general movies are often about two hours long and sometimes have different versions, namely, a theater version, a TV on-air version, other language versions (voices or subtitles), etc.
It is impossible for a laser disc to store all of such versions since the recording time of the analog moving picture data is limited to about one hour. Even if a laser disc stores audio data in channels along with a plurality kinds of very short moving picture data, the following problems occur:
(1) The plurality kinds of very short moving picture data overlap each other, generating a poor recording efficiency.
(2) If a plurality of subtitles are required, as many pieces of the same moving picture data as the plurality of subtitles must be created since the subtitle is inserted in the moving picture data.
(3) It is not possible for the user to change the current subtitle to another during a reproduction of moving picture data. To reproduce the desired subtitle, the user needs to reproduce a series of moving picture data including the desired subtitle from the beginning. That is, it is not possible for the user to change only the subtitle during a reproduction of moving picture data.
(4) If a plurality kinds of moving picture data have different numbers of audio channels for different languages and if a desired language is stored in a plurality of audio channels with different channel numbers, the user needs to change the audio channel number to maintain the desired language each time the user changes the moving picture data.
It is therefore an object of the present invention to provide a multimedia optical disc which may store a plurality pieces of video data, each of which is comprised of moving picture data and a plurality pieces of sub-data, such as audio data as voices and sub-picture data as subtitles, and with which the sub-data is managed easily even if different numbers of channels or different channels are assigned for the plurality pieces of video data, and to provide a disc reproduction apparatus and method for reproducing the multimedia optical disc.
The above object is achieved by a multimedia optical disc comprising: a data area for storing a plurality pieces of video data, wherein a piece of moving picture data and a plurality pieces of sub-data are interleaved in each of the plurality pieces of video data, wherein the plurality pieces of sub-data are reproduced selectively and synchronized with the piece of moving picture data, wherein the plurality pieces of sub-data are either of a plurality pieces of audio data and a plurality pieces of sub-picture data; and a management information area for storing a channel table in which a plurality of logical channel numbers are respectively related to a plurality of physical channel numbers for each of the plurality pieces of video data, wherein the plurality of logical channel numbers are shared by a certain numbers of pieces of video data, wherein the plurality of physical channel numbers are used to physically identify the plurality pieces of sub-data.
In the above multimedia optical disc, the data area may include a plurality of small areas over which a piece of video data is recorded, wherein each of the plurality of small areas includes: a first sub-area for storing moving picture data of a certain time period; and a plurality of second sub-areas for storing different pieces of sub-data, the different pieces of sub-data being reproduced simultaneously with the moving picture data of the first sub-area.
With the above construction, the channel table defines the relation between the logical channels and the physical channels, thereby correctly relating logical channels to physical channels even if different numbers of physical channels or different physical channels are assigned to the plurality pieces of video data. Accordingly, the sub-data can be managed correctly through entire pieces of video data. It is possible with this construction to prevent a reproduction of a piece of sub-data whose physical channel is not assigned to the piece of video data. It is also possible to prevent a malfunction in which a wrong or different piece of sub-data is reproduced when a piece of video data changes to another in reproduction.
In the above multimedia optical disc, each of the plurality of small areas may further include: a third sub-area for storing control information which includes a command specifying a piece of sub-data in the plurality of second sub-areas which should be reproduced with the moving picture data of the first sub-area, wherein the control information is effective through a period during which data of a piece of small area including the control information is reproduced.
With the above construction, a piece of sub-data can be changed dynamically to another with the use of the command during the reproduction of video data.
In the above multimedia optical disc, the control information may include a branch command which specifies a piece of video data as a branch destination, the branch command reflecting an interactive operation in a disc reproduction apparatus during a reproduction of video data.
With the above construction, the interactive operation in the disc reproduction apparatus is achieved. It is possible for the disc reproduction apparatus to maintain the reproduction the same kind of sub-data even if reproduction branches from one piece of video data to another by a user input in the interactive operation. In other words, even if a physical channel of sub-data before branching cannot be assigned to sub-data in the branch destination video data, an appropriate physical channel is assigned to the sub-data by referring to the channel table.
In the above multimedia optical disc, the channel table may include a flag for each of the plurality of logical channel numbers, the flag indicating whether a corresponding logical channel is effective.
With the above construction having the permission flag, it is possible to prevent a malfunction in which sub-data of physical channel not intended to be reproduced is reproduced.
The above object is also achieved by a disc reproduction apparatus for reproducing a multimedia optical disc which is comprised of a video data area and a management information area, wherein the video data area stores a plurality pieces of video data, wherein a piece of moving picture data and a plurality pieces of sub-data are interleaved in each of the plurality pieces of video data, wherein the plurality pieces of sub-data are reproduced selectively and synchronized with the piece of moving picture data, wherein the management information area stores a channel table in which a plurality of logical channel numbers are respectively related to a plurality of physical channel numbers for each of the plurality pieces of video data, wherein the plurality of logical channel numbers are dealt with in the disc reproduction apparatus, wherein the plurality of physical channel numbers are used to physically identify the plurality pieces of sub-data of the multimedia optical disc, the disc reproduction apparatus comprising: reading means for reading data from the multimedia optical disc; channel number holding means for holding a logical channel number; determining means for determining a physical channel number to be reproduced based on the channel table read by the reading means and the logical channel number held by the channel number holding means; selecting means for selecting a piece of sub-data among a plurality pieces of sub-data read by the reading means, the piece of sub-data corresponding to the physical channel number determined by the determining means; and reproducing means for reproducing a piece of moving picture data read by the reading means and the piece of sub-data selected by the selecting means.
With the above construction, the channel table defines the relation between the logical channels and the physical channels, thereby correctly relating logical channels to physical channels even if different numbers of physical channels or different physical channels are assigned to the plurality pieces of video data. Accordingly, the sub-data can be managed correctly through entire pieces of video data. It is possible with this construction to prevent a reproduction of a piece of sub-data whose physical channel is not assigned to the piece of video data. It is also possible to prevent a malfunction in which a wrong or different piece of sub-data is reproduced when a piece of video data changes to another in reproduction.
The above disc reproduction apparatus may further comprise: table retaining means for retaining a channel table read by the reading means; and table updating means for updating the table retaining means each time the reading means reads a new channel table, wherein the determining means reads, from the channel table retained by the table retaining means, a physical channel number corresponding to the logical channel number held by the channel number holding means each time the table updating means updates the table retaining means, wherein the selecting means selects a piece of sub-data which corresponds to the physical channel number read by the determining means.
In the above disc reproduction apparatus, the channel table may include a flag for each of the plurality of logical channel numbers, the flag indicating whether a corresponding logical channel is effective, wherein the disc reproduction apparatus further comprises: receiving means for receiving a sub-data switch instruction input by a user, wherein the determining means further includes: table searching means for, when the receiving means receives the sub-data switch instruction, searching the channel table retained by the table retaining means to detect a logical channel number having a flag indicating that a corresponding logical channel is effective, wherein the determining means reads the logical channel number detected by the table searching means and also reads a physical channel number which corresponds to the detected logical channel number, wherein the channel number holding means holds the logical channel number read by the determining means, wherein the selecting means selects the piece of sub-data which corresponds to the physical channel number read by the determining means.
With the above construction, the interactive operation in the disc reproduction apparatus is achieved. It is possible for the disc reproduction apparatus to maintain the reproduction the same kind of sub-data even if reproduction branches from one piece of video data to another by a user input in the interactive operation. In other words, even if a physical channel of sub-data before branching cannot be assigned to sub-data in the branch destination video data, an appropriate physical channel is assigned to the sub-data by referring to the channel table.
In the above disc reproduction apparatus, the piece of small area of the multimedia optical disc may store control information which includes a command specifying a piece of sub-data in the plurality of second sub-areas which should be reproduced with the moving picture data, wherein the control information is effective through a period during which data of a piece of small area including the control information is reproduced, wherein the receiving means further receives an instruction which instructs whether to execute the command, wherein the determining means, when the receiving means receives an instruction to execute a command, reads the logical channel number specified by the command received by the receiving means and also reads a physical channel number which corresponds to the read logical channel number, wherein the selecting means selects the piece of sub-data which corresponds to the physical channel number read by the determining means.
With the above construction, a piece of sub-data can be changed dynamically to a desired piece during the reproduction of video data.